The present invention relates to a cooling-water heating type heater, and more particularly, to a cooling-water heating type heater that heats cooling-water for heating the interior of a vehicle.
The most typical vehicles are vehicles with an engine as a driving source using gasoline, light oil and the like as energy sources at present, but it is increasingly necessary to find a new energy source for the vehicle using the energy sources too due to various causes such as environmental pollution and reduction of oil reserves, and currently, a vehicle using fuel cells for an energy source is one of the technologies closest to practical use.
The vehicle using fuel cells, however, cannot use a heating system using cooling water, unlike the vehicles with engines using oil as an energy source in the related art. That is, in the vehicles with an engine as a driving source using oil as an energy source in the related art, the engine generates a large amount of heat and a cooling-water circulation system for cooling the engine is mounted, and the heat that the cooling water takes from the engine is used for heating the interior of the vehicles. However, there is a limit in using the heating system for the vehicles using fuel cells, because their driving sources do not generate as much heat as the engine.
Therefore, various studies have been conducted for the vehicles using fuel cells, such as adding a heat pump to the air-conditioning system to use the heat pump as a heat source or mounting a specific heat source such as an electric heater. In the studies, the electric heater is used at present over a wide range, because it can more easily heat cooling water without a large influence on the air-conditioning system.
FIG. 1 shows Japanese Patent Laid-Open Publication No. 2008-056044 (“apparatus for heating heat carrier and air-conditioning system for vehicle using the same”, 2008.03.13), which is one of cooling-water heating type heaters of the related art.
The cooling-water heating type heater disclosed in Japanese Patent Laid-Open Publication No. 2008-056044 has a structure that more effectively heats cooling-water by increasing heat transfer efficiency from a PTC electrode plate that is a heating source to the cooling water, by disposing plate-shaped fins on the top and bottom of the PTC electrode plate such that the cooling water passes the plate-shaped fins.
The cooling-water heating type heater, however, has a problem in that it is difficult to achieve a sufficient effect of heating the cooling-water, and other problems including the problem are described below.
First, there is a problem in that since the heating source (PTC electrode plate) is added as a separate part, the number of parts increases and the volume and weight also increase. Second, the heat generated from the PTC electrode plate fails to fully transfer to the cooling water and some of the heat transfers to the outside, resulting in heat loss. Third, since there are various objects on an insulating layer on the heat transfer path from the PTC electrode plate to the cooling water, thermal resistance increases and heat transfer efficiency correspondingly decreases. Fourth, the design, including the cooling-water pipe lines or electric wire circuit, is complicated, when the cooling-water heating type heater is mounted on a vehicle, and the cooling-water heating type heater is difficult to mount, because the volume is large.
That is, it is required to develop a cooling-water heating type heater capable of effectively heating cooing-water and being easily manufactured and mounted while reducing the volume, weight, and cost.